Our report describes a fourfold variation in the rate of hospital bed use by older people admitted as an emergency. This is driven in equal part by differences in length of stay and rates of admission for older people. Our working hypothesis was that we would be able to link the use of hospital beds with other factors like spend on social care, the number of community beds, and the number of GPs, but we couldn't demonstrate a relationship.

The variation in these other factors was just as great if not greater than the variation in bed use and no clear pattern emerged. The only factor that those areas with the lowest use of beds had in common was that a high number of them had a history of joint working between health and social care.

So why is there this degree of variation across the NHS? I have come to see such huge differences in the care that people receive in different parts of the country as a fact of life.

I write reports with the hope of stimulating action to reduce variation, but I have lost the outrage expressed by those outside the system. I have found staggering variation in most of the work that I have done at the King's Fund; ten fold variation in rates of GP referral, four fold variation in community nurse productivity, five fold variation in investment in workforce development.

Variation almost seems to be the defining characteristic of the NHS. Variation that is tolerated.

So why does it exist? Short answer – nobody knows, or at least I am not aware of any evidence that provides a coherent answer. One reason for the failure in joint working is likely to be that the NHS rewards individual organisational performance and not collaborative working.

But why is it that when we know that having senior doctors at the front door of the hospital, regular ward rounds, dedicated assessment units (of adequate size), specialist support for dementia, stroke and geriatric patients will all reduce length of stay, hospitals do not universally implement these.

Before I joined the King's Fund I worked in the NHS. I held a number of senior leadership roles and I am currently a non executive director in an acute trust. My observations from firsthand experience would be that the NHS is under managed and over bureaucratised.

As a manager I had a life of endless meetings and paperwork with little to demonstrate the value I was adding. In this context pursuing best practice, and working across boundaries can be very hard. Especially if you are not working effectively with clinical leaders, who ultimately can change the behaviour of their colleagues.

In my last job we developed endless strategies that came to naught because of resistance from clinicians. I am sure there are many other factors at play, but it leaves me with the reflection that while it's valuable to expose the variation, the important question is why is it there in the first place?